Priority is claimed to PCT/GB00/01641 filed Apr. 28, 2000, which claims priority to Great Britain Application Number 9910468.9 filed May 7, 1999.
1. Field of the Invention
This invention is concerned with improvements in a dispensing device and is particularly concerned with the dispensing of a metered quantity of a liquid from the dispensing device in an uninterrupted method of operation of the dispensing device.
2. Description of the Related Art
Cleansing products are commonly supplied as a liquid in concentrated form which requires dilution with water before use. Thus, a measured quantity of the cleansing product is added to a known quantity of water for the most efficacious result.
Normally, the measured quantity of the concentrated cleansing product is introduced into a conventional graduated spray bottle which is thereafter filled with water. The water/cleansing product mixture may entirely fill the spray bottle, or, the water may be added until an appropriate graduation mark is reached by the water/cleansing product mixture.
Similarly, a measured quantity of a concentrated cleansing product may be introduced into any suitable receptacle in which, or into which, a requisite amount of water is provided. If an operative complies with the requirements for achieving the most advantageous mixture, there is little likelihood that any damage may be caused to the surfaces being cleaned or that the health of the operative may be put at risk if they are subjected to concentrations of the mixture above the recommended dosage levels.
Unfortunately, it is human nature to believe that the efficacy of a mixture may be enhanced by increasing the dosage levels of a concentrate in a mixture. Thus, an operative may add double or more of the recommended dosage of a concentrated cleansing product to a mixture with deleterious results.
The objects of the present invention are therefore to overcome or mitigate the drawbacks of known dispensing devices and their method of operation.
Thus the present invention conveniently provides a dispensing device for delivering a metered quantity of a liquid, the dispensing device comprising a reservoir, priming means for priming the reservoir, when the dispensing device is in use, with a metered quantity of a liquid, the dispensing device also comprising a delivery means for delivering, when the dispensing device is in use, said metered quantity of said liquid from the reservoir, characterised in that, the dispensing device further comprises inhibiting means for:
a) preventing the interruption and reversal of a priming stroke of the priming means; and,
b) preventing the interruption and reversal of a delivery stroke of the delivery means,
and wherein the priming and delivery means comprises a lever pivotally mounted on the dispensing device, characterised in that the lever includes at least two arcuate surfaces and the inhibiting means comprises at least two locking members located one each adjacent a respective one of the arcuate surfaces, wherein, when the dispensing device is in use, the locking members operate in concert and are moved between:
a) a first operative condition in which a first arcuate surface engaging portion of each locking member is brought into engagement with its respective arcuate surface to prevent the interruption and reversal of the priming stroke of the priming means until the priming stroke thereof is completed; and,
b) a second operative condition in which a second arcuate surface engaging portion of each locking member is brought into engagement with its respective arcuate surface to prevent the interruption and reversal of the delivery stroke of the delivery means until the delivery stroke is completed.
Preferably, the locking members each comprise a triangular block pivotally mounted on the dispensing device, wherein when the dispensing device is in use, the triangular blocks are moved simultaneously into their first operative condition or into their second operative condition by spring means.
Conveniently, the spring means comprises a generally xe2x80x9cCxe2x80x9d shaped leaf spring opposite ends of which leaf spring are arranged to act one on each of the triangular blocks respectively to urge the triangular blocks into their first operative condition or their second operative condition at or towards opposite ends of the arcuate surfaces associated therewith.
Preferably, the dispensing device comprises stop elements located at the opposite ends of the arcuate surfaces, the stop elements being effective, when the dispensing device is in use:
a) to engage the triangular blocks at a first end of the arcuate surfaces to cause the triangular blocks to pivot simultaneously about their respective fulcrum points into their first operative condition in which they are set to prevent the interruption and reversal of a subsequent priming stroke of the priming means; or,
b) to engage the triangular blocks at a second end of the arcuate surfaces to cause the triangular blocks to pivot simultaneously about their respective fulcrum points into their second operative condition in which they are set to prevent the interruption and reversal of a subsequent delivery stroke of the delivery means.
Conveniently, the relative positions of the respective stop elements at the opposite ends of the arcuate surfaces are variable in order to alter the length of the priming and delivery strokes of the priming and delivery means respectively.
Preferably, the arcuate surface engaging portions of the triangular blocks and/or the respective arcuate tracks engaged thereby are each provided with a friction coat or surface finish to enhance the locking engagement of the triangular blocks with their respective arcuate surfaces should an operative try to interrupt and reverse the priming or delivery strokes of the priming means or the delivery means respectively when the dispensing device is in use.
In one embodiment, provided by the present invention the lever includes two arcuate surfaces formed one on either side of an arcuate rib formed integrally with the lever, and a centre of curvature of the arcuate rib is coincident, or substantially so, with a pivotal axis of the lever.
Preferably, the dispensing device comprises one locking member provided by a triangular block on opposite sides of the arcuate rib adjacent their respective arcuate surfaces of the arcuate rib.
Conveniently, the dispensing device comprises an over-ride means for engagement with the triangular blocks, when the dispensing device is in use, to move the triangular blocks into inoperative conditions in which arcuate surface engaging portions of the triangular blocks are held out of engagement with a respective one of the arcuate surfaces.
The present invention also provides a method of dispensing a metered quantity of a liquid from a dispensing device, the method comprising the steps of priming a reservoir with a metered quantity of the liquid and delivering the metered quantity of the liquid from the reservoir characterised in that the method also comprises the steps of:
a) preventing the interruption and reversal of the priming stroke until the reservoir has received the full metered quantity of the liquid; and,
b) preventing the interruption and reversal of the delivery stroke until the reservoir has been emptied of the full metered quantity of the liquid.